1. Field of the Invention
This invention relates to radomes and more particularly to a radome and reflector antenna pair having ease of installation and improved reflection/transmission characteristics.
2. Description of Related Art
Reflector antennas are used in, for example, communications systems. Radomes are used to cover the open end of the reflector to minimize wind loading and antenna performance degradation due to environmental fouling of the antenna reflector and or feed assembly.
Reflector antennas are subject to expansion and contraction due to temperature change. The reflector and the radome are formed from different materials, typically having different expansion coefficients. The interconnection between the radome and the reflector should accommodate differential expansion between the radome material and the reflector material, without compromising the mechanical attachment integrity or environmental seal between the radome and the reflector. Also, the interconnection should not create a stress that may deform the precision surfaces of the reflector and degrade the overall antenna reception sensitivity and or radiation patterns.
Prior radomes utilize a dielectric fabric, fiberglass or a molded dielectric plastic cover attached with a plurality of spring and or screw connections around the periphery of the reflector or a reflector shroud. The associated plurality of springs, clips, screws, and or brackets are a significant burden during installation and or service of the reflector antenna high upon radio towers or other difficult to access locations.
The radome also creates an impedance discontinuity within the RF signal path that generates a return loss due to RF reflections off of the radome directly or via further reflections back into the antenna feed. United Kingdom Patent Application No. 2120858 by Young, et al. published Dec. 7, 1983 discloses that a reflector antenna radome may be formed with concentric outer and inner parabioloidal portions so that a significant portion of reflected RF energy that may otherwise be aligned to reflect back into the antenna feed is instead directed by the inner parabioloidal portion to the backside of the feed assembly sub reflector where RF absorbing material may be located. However, the significantly reduced focal length of the inner parabioloidal portion necessary to direct the RF energy to the back of the sub reflector causes the radome to have a significant center protrusion and associated additional structural mass, negatively affecting the windload and or other structural requirements of the radome, reflector antenna and support structure. Also, the center protrusion provides a surface for snow and or ice build up.
Competition within the reflector antenna industry has focused attention on RF performance, structural integrity, materials and manufacturing operations costs. Also, ease of installation and service is a growing consideration in the reflector antenna market.
Therefore, it is an object of the invention to provide an apparatus that overcomes deficiencies in the prior art.